Generic camshafts are sufficiently well known and are used in particular for the variability with regard to the valve opening duration. In order to enable a long-term reliable operation, it is necessary to mount both the inner shaft and the outer shaft in an axial direction. In particular, this is also of great importance since the cams pinned to the inner shaft can only be adjusted effortlessly if the pins passed into corresponding elongated holes of the outer shaft do not rub, i.e. come into contact with an edge of the respective elongated hole. In order to adjust such adjustable camshafts, a phase adjuster is normally used with a rotor and a stator, wherein the rotor is fixedly connected to the inner shaft and fixedly to the stator of the phase adjuster in the axial direction. The stator of the phase adjuster is in turn connected to the outer shaft in the axial direction. Both the outer shaft as well as the inner shaft are thus fixed in the axial direction by means of the phase adjuster, i.e. specifically by means of the stator and the rotor of the phase adjuster.